Just days after the champagne bottles had been uncorked, Brighton served up a sobering experience and in the process emphatically revived their mission to scramble into the play-offs.

Brightonwere not simply party poopers, they gatecrashed the King Power Stadium and stole the streamers and booze in a clinical, stylish display that leaves them two points behind Reading in sixth place.

It was only Leicester’s first defeat in 22 games and hardly the evening the crowd of nearly 30,000 would have anticipated but will do little to sabotage an excellent season, even if Pearson’s mood was dark.

“It’s not a great night and it’s down to earth with a bump,” he said. “The players don’t feel great and to celebrate you must do it with a performance and we didn’t get it. This was a wake-up call.

“We looked a shadow of what we’ve been about this season and too many individuals were way off the mark. There is an element of people maybe relaxing because we’ve already achieved promotion but we’ve got five games left and want to win the title.”

Pearson’s success cannot be underestimated and should hopefully act as a reminder to panicking chairmen that changing managers does not always yield a shift in fortune. After the bitter disappointment of defeat in last season’s play-offs, promotion has been achieved against a backdrop of uncertainty with expiring contracts and the omnipresent pressure of ending the club’s long exile from the Premier League.

Not even this reality check could damage the feel-good factor. Leicester had not suffered a league defeat since their meeting at Brighton in early December and were dreadful for much of the night.

Brighton had already been threatening frequently before taking a 17th-minute lead through a Stephen Ward header. They increased their lead seven minutes later, with Ward’s exquisite cross from the left presenting Jesse Lingard with another simple header. “Premier League, you’re having a laugh” came the chant from the 689 Brighton fans in the corner.

Leicester made a marginal improvement in the second period, with substitute Chris Wood striking a post, but the outstanding Leonardo Ulloa bludgeoned in a third goal and added a fourth ten minutes from time.

Gary Taylor-Fletcher, a Leicester substitute, swept home a consolation goal but this was hardly an accurate reflection of an outstanding campaign.

Brighton’s season, however, is still alive. Óscar García, the manager, said: “It’s a massive result for us because it’s against a Premier League side. We are well positioned but I am only focused on the next game and I hope the players are the same.”